In the U.S., current law holds that for a law enforcement officer to stop and request identification, the officer needs at least some sort of articulable basis for doing so (Terry stop). The key word here, though, is “stop.” Electronic surveillance of a public space, though, involves stopping nobody. It’s not clear to me that passive identification involves either a “search” or “seizure” within the traditional meaning of the 4th Amendment. We’ll see what the courts think, though.